If I had to point out one major difference between educated people who make ordinary incomes and those who make big incomes, I would say that the latter, the super-successful, are much, much better at looking out for their self-interests.

Indeed, the survey research for my book Business Brilliant revealed enormous disparities between self-made millionaires and people with ordinary middle-class incomes when it comes to unscrupulous, "Machiavellian" behavior.

Almost 90 percent of the millionaires in the survey agree that "it's important in negotiations to exploit the weaknesses in others." The middle class? Just 24 percent. About 80 percent of the millionaires say that "coming out on top in business dealings is paramount." For the middle-class, just 31 percent agree. And a full 77 percent of millionaires say, "I do not have any problems confronting my business associates." Fewer than 13 percent of the middle class say the same. On this particular point, the multi-millionaires, those who have a net worth higher than $10 million, are nearly unanimous. More than 98 percent say they have no problem with confrontation in business.

Get the picture? The numbers suggest that what separates the super-successful from everyone else is that they play to win, exploit weakness when they find it, and defend their interests even if it requires a showdown with a partner or friend. Does this mean that the super-successful are maestros of Machiavellianism? Most super-successful people think so. Almost 78 percent admit that "being Machiavellian is essential to becoming wealthy." The middle-class, though, prefer to think the business world is a kinder, gentler place. Fewer than 17 percent say that Machiavellianism is essential to becoming wealthy.

How Machiavellian are you? In order to find out, you don't need to read The Prince, Machiavelli's 16th-century treatise on power. You can take an online test devised years ago by social psychologists Richard Christie and Florence L. Geis to measure Machiavellianism as a distinctive personality trait. Their 20-question survey will give you an instant assessment of where you rank on the Machiavellian spectrum.

In general, social scientists define Machiavellianism as corresponding to people who would respond affirmatively to the following questions:

Are you more upset by inefficiency than injustice?

Are you less emotionally affected by social norms and social pressures than most people?

Are you good at identifying optimal strategies for getting what you want?

Do you consider your attitude toward business as cool, detached, and rational?

Do you consider yourself opportunistic?

Now let's say you disagree with most of these characterizations. Injustice upsets you more than inefficiency. You consider opportunism to be distasteful and destructive. You regard your sensitivity to social norms and pressures as an asset in doing business with people. Does that mean you can't be financially successful? Not at all.

Remember that at least 22 percent of the super-successful in my survey don't agree that Machiavellianism is essential to success. So scoring low on the Machiavellian personality test is hardly a barrier to your success. But if that's the case for you, it's important to remember that your way of thinking does put you in the minority when dealing with the wealthy and powerful. Next time you're ready to negotiate a deal or sign a business agreement, keep these Business Brilliant survey results in mind. Whenever you meet people who seem to display these Machiavellian beliefs and behaviors, it's not paranoid to wonder if they're ready to pick your pockets in a deal. They just might be.

Most people don't consider Machiavellian tendencies during their business dealings at all. Only 36 percent of middle-class people say that "in negotiations I expect people to try to take advantage of me." About 70 percent of self-made millionaires, however, have that expectation. So even if you're not out to screw the other guy, seven out of ten super-successful people will assume that you are.

Whether you consider yourself Machiavellian or not, you need to be aware most every successful person you deal with is--a phenomenon that could help you win.

You can join Lewis Schiff and like-minded rider entrepreneurs next month at the first-ever Inc. Riders Summit, a three-day motorcycleroad trip through the Nevadadesert for entrepreneurs. For more information about the ride, the entrepreneur-led business sessions, or the networking, click here.